Kinetic models of the glucose regulatory systems are being developed for man and other animals in collaboration with several experimental groups. These include models of the distribution, metabolism and receptor binding of insulin, using data from both radioiodinated and native insulins, and the production and utilization of glucose as elucidated by tracer studies with labeled glucose, alanine and lactate. Models of the role of insulin in the control of glucose utilization and production are also being studied. The kinetics of ketones in man have also been studied and modeled.